Author Topic: Colors of Aurora  (Read 476 times)

Øivind Tøien

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Colors of Aurora
« on: April 02, 2022, 12:59:03 »

Aurora at high latitudes typically takes on almost monochromatic shades of green. These images are from a rare event here in Fairbanks past 3am last night, showing an unusual amount of colors in the blue and red spectrum. The colors are not the result of shifted color balance as daylight white balance was used on the camera. While the colors were detectable by eye, the human eye is not very sensitive to colors at these low light intensities opposed to the camera sensor.

#1



#2



#3



#4



#5



#6



Eventually it started to fade in contrast, but colors remained for a while. Seeing these images appear on the back screen of the D500 is an event I will remember for a while.
#7


Øivind Tøien

rosko

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Re: Colors of Aurora
« Reply #1 on: April 02, 2022, 13:57:59 »
Superb images, Øivind !

I like colours and dynamic effect.

Francis.
Francis Devrainne

Brute

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Re: Colors of Aurora
« Reply #2 on: April 02, 2022, 17:28:53 »
Very Nice. Thank You for sharing  :)
Heard that it could be seen all the way down threw Central and Eastern Washington and Oregon.
Unfortunately I'm in the NW corner of Oregon and didn't see it.
Ken Smith

Akira

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Re: Colors of Aurora
« Reply #3 on: April 02, 2022, 22:41:35 »
#5 looks amazing!

I've heard that the reddish color of the aurora is often observed at lower latitude.  I wonder what caused these multiple colors observed in Fairbanks.
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Anthony

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Re: Colors of Aurora
« Reply #4 on: April 02, 2022, 23:30:05 »
These are breathtaking.
Anthony Macaulay

golunvolo

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Re: Colors of Aurora
« Reply #5 on: April 03, 2022, 01:26:40 »
These are breathtaking.
Agreed with all above, specially this one.

Thanks for sharing it!

Øivind Tøien

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Re: Colors of Aurora
« Reply #6 on: April 03, 2022, 04:22:29 »
Thanks for the comments everybody. It was pretty breathtaking just seeing these appear on the camera, considering how mellow the visual impression was by direct eye. Just to illustrate how close the view on the camera screen was to the final image, here is a comparison from my cell phone so a bit more saturated:



Akira, #5 is certainly my favorite too. Yes, the red dominance in auroras are pretty common when it happens to reach lower latitudes, lots of report from the "lower 48" on this occasion at the Spaceweather site. Apparently the reds are caused by particles causing excitation of oxygen high up in the atmosphere where there is less oxygen, and causing different excitation than when it hits at lower altitudes where oxygen is more dense and results in colors in the green. Blue is apparently caused when particles are hitting ionized nitrogen high in the atmosphere. So there we have it  - RGB.  :D . What was "suspicious" on this occasion was that while the aurora oval displayed at spaceweather.com showed very high activity with red in the heat map, the aurora cam north of Fairbanks indicated very mellow green activity to the north, but notably with some spurs of the deep blues shown above, so I sensed something special was going on. My view is in the southerly direction, but for a long time it was very diffuse with colors blending into each other. This contrasted the beginning of this event the evening before that was quite intense but very green with just a little purple.
Øivind Tøien

Fons Baerken

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Re: Colors of Aurora
« Reply #7 on: April 03, 2022, 09:25:21 »
It must be a truly wonderful experience!

Øivind Tøien

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Re: Colors of Aurora
« Reply #8 on: April 03, 2022, 10:03:48 »
Thanks Fons, we still have a sunspot larger than the size of earth facing us, and it is spring time which tend to increase the chance of aurora, so it is worth keeping a watch. Spaceweather.com had a report from Europe as far south as Denmark. But again it is necessary to use the camera as ones eye at these subtle auroras, which I find is part of the fun and thrill. Admittedly when hitting the bunk shortly after this event I spent a little time to calm down from the quiet excitement.
Øivind Tøien

John Geerts

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Re: Colors of Aurora
« Reply #9 on: April 03, 2022, 11:22:12 »
Beautiful and amazing, Øivind

Akira

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Re: Colors of Aurora
« Reply #10 on: April 03, 2022, 16:19:20 »
Akira, #5 is certainly my favorite too. Yes, the red dominance in auroras are pretty common when it happens to reach lower latitudes, lots of report from the "lower 48" on this occasion at the Spaceweather site. Apparently the reds are caused by particles causing excitation of oxygen high up in the atmosphere where there is less oxygen, and causing different excitation than when it hits at lower altitudes where oxygen is more dense and results in colors in the green. Blue is apparently caused when particles are hitting ionized nitrogen high in the atmosphere. So there we have it  - RGB.  :D . What was "suspicious" on this occasion was that while the aurora oval displayed at spaceweather.com showed very high activity with red in the heat map, the aurora cam north of Fairbanks indicated very mellow green activity to the north, but notably with some spurs of the deep blues shown above, so I sensed something special was going on. My view is in the southerly direction, but for a long time it was very diffuse with colors blending into each other. This contrasted the beginning of this event the evening before that was quite intense but very green with just a little purple.

Thank you for the details.  I wonder if that unusual colors of the aurora has something to do with the sunspot activity you captured.
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Bill De Jager

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Re: Colors of Aurora
« Reply #11 on: April 03, 2022, 18:43:49 »
I'll be the third person to use the word "amazing".  The effect is majestic.

I've been fortunate enough to see the aurora only once.  That was at a surprising latitude of only 36 degrees north.  The only color was red, and I thought it was a forest fire in the mountains (albeit not quite the right shade of red) until it rose into the sky and was no longer connected to the ground.

Nasos Kosmas

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Re: Colors of Aurora
« Reply #12 on: April 03, 2022, 20:17:34 »
Never had this experience must be unique!
Thank you Oivid!

ColinM

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Re: Colors of Aurora
« Reply #13 on: April 03, 2022, 22:10:44 »
Breathtaking Øivind

Seeing these images appear on the back screen of the D500 is an event I will remember for a while.

I can well believe it

Øivind Tøien

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Re: Colors of Aurora
« Reply #14 on: April 04, 2022, 09:40:56 »

Thanks so much for the enthusiastic comments everybody.
Here is an article by science writer Ned Rozell that explains how red aurora appears and under what conditions:
https://www.gi.alaska.edu/alaska-science-forum/red-aurora-rare-enough-be-special

[BTW, I thought I was a bit heavy handed with color noise reduction causing the rays to be more blurry than needed, so I updated the last images with slightly modified versions.]
Øivind Tøien